Aqua performance is a mixed bag, but is
generally acceptable. Things that were fast in DP2 remain fast (or faster) in DP3. Opaque
window dragging is very snappy and does not appear to suffer any slow-down due to the
transparent window shadows. The translucent menus come down only marginally slower than
the plain ones did in DP2, and scrolling over menu items suffers no perceptible speed hit.
Buttons, checkboxes, and other control widgets are not particularly CPU intensive and
behave innocuously.

The first signs of CPU loading come when
large motions are required. Scrolling windows (both list and icon view) in the Finder is
fast in most circumstances. Horizontal scrolling in list view windows is noticeably
slower, however. Opaque resize is inordinately slow for no good reason (it's so slow that
I must assume it's some sort of implementation bug in DP3). "Sheets" (those
attached dialogs that seem to slide out from under the window title bars in Mac OS X) miss
a few frames on the G3/400. The genie effect stutters even more noticeable in some
circumstances, but the total time taken to minimize or maximize seems constant. Frames of
animation are dropped, but the window rarely takes any more time to appear or disappear.

The genie effect

"Sheets"-style
dialogs

The G4/350 handled all the
transformations effects (sheets, genie, etc.) noticeably better than the G3/400, even with
only 64MB of RAM (which is the minimum RAM requirement for Mac OS X). Further, the
impressive ability of QuickTime movies to continue to play while they're being
"genie-ed" during a maximize or minimize operation isn't even attempted when DP3
is running on the G3. Instead, what you see is a white outline of the window with no
picture of any kind where the movie would be. Try the same operation on the G4 and it not
only displays the playing movie while max/minimizing, it actually appears to get more
frames of animation than the ostensibly "faster" (in MHz) G3 does with its empty
window.

As responsive as DP3 is on the G4 (and
even on the G3), switching back to Mac OS 9 on the same machine results in a noticeable
improvement. So while DP3 may not be unacceptably slow, it is slower than Mac OS 9 on the
same hardware. What constitutes an "acceptable" drop in performance is likely to
be a personal issue.

The G4/350 really does feel like the
faster machine in DP3 under casual usage. But the limited RAM on the G4 test system
eventually gets it into trouble. The classic environment alone can easily eat up 64MB of
RAM. Launch a few classic apps, open a bunch of Finder windows, launch a few Cocoa or
Carbon apps, and you quickly get into The Land of Thrash. Classic's enormous appetite for
system resources is a real killer. It not only wants a huge chunk of RAM, it also
dominates CPU usage on an otherwise idle system.

Ouch.

Keep in mind that this is an idle system,
and as scary as those stats appear, they does not mean that there's less than 10% of the
CPU left for other tasks. Start actually using the Finder, for example, and Classic
immediately drops to less than 30% CPU usage. Genie a window and suddenly the
WindowManager process leaps to the top of the table with ~20% CPU usage. The bottom line
is that the numbers in the "%CPU" column will always total to 100%. But while
every other process is essentially idle (either in i/o wait for just plain not doing
anything), the Classic environment is glad to slurp up every CPU cycle passed up by the
other apps (which it distributes to each of the classic apps running inside it). Of
course, this being a preemptive multitasking system, when the other apps actually need
cycles, they can just take them.

Classic's RAM usage is more of a problem
than its CPU usage, since a shift in RAM usage often means hitting the disk (which is much
slower than merely redistributing CPU cycles). If you never launch Classic, a 64MB machine
is about as usable as a 64MB machine under Mac OS 9. You can actually launch more apps on
a 64MB DP3 machine, but you pay the price in swap activity. Still, at least you have the
option. A 64MB Mac OS 9 machine will just "run out" of RAM and complain. And if
you try to crank up Mac OS 9's VM system to much more than double your real RAM, you'll
see thrashing that makes DP3 look polite and docile.

It's not clear how much debug/testing
"fat" remains in DP3. As things stand, DP3 would probably run acceptably on a
64MB machine while simultaneously running updated versions of common household apps: word
processing, email, web browsing, spread sheets, etc. The key word here is
"updated," meaning Carbon or Cocoa. In the time between now and Mac OS X's
commercial launch, Apple had better be lighting fires under the big-name app vendors to
Carbonize.